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. TATES PATENT OFFICE.

JOSHUA H. ROBERTSONJOF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO I CHARLESW. RANDALL, OF SAME PLACE.

EXPLOSIVE COMPOUND.

SPECIFICATION forming part of Letters Patent No. 307,989, dated November11, 1884.

'iipiilieatlon'fil'eilDecember l, lass. Renewed Oet0ber22, 1884. (Nospecimens.)

To all whom it may concern:

Be it known that I, JOSHUA H. ROBERTSON, of the city and county of SanFrancisco, State of California, have invented a new, useful. andImproved Explosive Compound; and I hereby declare the following to be afull specification of the same, sufficient to enable a person skilled inthe art to which my invention appertainsto make, compound, and use thesame. a 1

My invention consists in combining anhydrous sodium su'lphatecommonlyknown as sulphate of soda -with nitro-glycerine, thus forming a new andimproved explosive compound; and among the advantages possessed by mycompound are diminished cost of production, increased tenacity ofunioubetween the ingredients, and a material diminution of n'ox ionsfumes. A proportion of nitro-glycerine which, in a compound consistingof infu'sorial or silicious earth and nitro-glycerine, cannot beexploded, can in my compound be readily and certainly detonated, and,being non-deliquescent, it is not readily affected by moisture.

To produce my compound I place sixty-five pounds of finely-pulverizedanhydrous sulphate of soda in a wooden tank or other suitablereceptacle, and gradually add thereto thirty-five (35) pounds ofnitro-glycerinc. I stir the mixture by a wooden rake or other suitableutensil until the nitro-glycerine and sulphate of soda are thoroughlyincorporated together, when the compound is ready to be placed intocartridges for use.

I do not desire to limit myself to the proportions of the ingredientsherein stated, but give the foregoing as an example merely, the relativeproportions being susceptible of considerable change, in accordance withthe desired strength or grade of the explosive.'- The strength of theexplosive may be increased or diminished by increasing or diminishingthe proportion of nitro-glycerine, the illustration given being taken asa standard, care being taken not to add sufficient nitro-glycerine toreduce the compound to a soft or pasty eonsisteney. When properlyprepared, the explosive is of a granular or pulverulent character.

The manner of firing my explosive is the same as that in common use--bymeans of a detonator, either with or without a primingcharge.

I obtain my anhydrous sulphate of soda at then ground to animpalpablepowder; In this condition the product is ready for use.

I am aware that thisprocess is old, and therefore do not claim it. Fromwhatever source the anhydrous sulphate of soda is obmay contain shall beexpelled or neutralized before combining it with the nitro-glycerine.

I am aware that various infusorial, silicious, and volcanic earths havebeen mixed with nitro-glycerine; also of the United States patent ofShatfner, N 0. 93,7 52, in which anhydrous sulphate of lime has beenmixed with nitroglyccrine and allowed to set to form a solid mass; alsoof the United States patent to Fowler, granted February 12, 1878, inwhich non hydrated sodium sulphate is described as mixed with otheringredients and with nitro.- glycerine.

In an application filed by mein the United States Patent OfficeFebruary.,13, 1884, No; 120,631, and allowed October 18, 1884, I haveclaimed, broadly, a mixture of granular auhydrous salt andnitro-glycerine, and I claim in this application only the specificelements and in substantially the proportions specified.

Having described my invention, .what I claim, and desire to secure byLetters Patent, 1s-

A new and improved explosive compound, consisting of anhydrous sulphateof soda and nitro-glycerine.

In testimony that I claim the foregoing I have hereunto set my hand andseal this 20th day of November, 1882.

JOSHUA lI. ROBERTSON [L 8.]

Witnesses: V

-- G. W. M. SMITH, WM. L. HIGGINS.

'taiued, it" is essential that anyffee acid it"

